Ethers of z



t d S a es Pat 2,976,291 I ETHERS 0F Z-PIPERIDYLPHENYLMETHANOLS I Robert Michel Jacob,Abl0n-sur-Seine, and Nicole Marie Joseph, Paris,-France, assignors to Societe des Usines Chimiques Rhone-Poulenc, Paris, France, a corporation of France No, Drawing. Filed July 17, 1958, Ser. No. 149,075

Claims priority, application France Aug.'1, 1957 10 Claims. (Cl. 260-2945) 7 This invention relates to new ethers of 2-piperidylphenylmethanols and to processes for their preparation. Z-piperidylphenylmethanols of the general formula:

racemate in two stereoisomeric forms A and B (cf. K. E.

Crook and S. H. McElvain, J. Amer. Chem. Soc. 52, 4006 (1930) Form A is generally obtained as the main product on catalytic reduction of 2-benzoylpyridine optionally substituted in the benzene nucleus. When one or other of the two forms or a mixture thereof is treated with thionyl chloride in the cold and the chloro derivative thus obtained is hydrolysed, for example by means of an aqueous solution of a mineral acid or of silver nitrate, a single form only is obtained which is, by convention, designated form B. These two forms A and B of the 2-piperidylphenylmethanols are also distinguished by systematic differences in their infra-red spectra. It. has been established that form A has the erythro and form B the three structure respectively. A

This invention is concerned only with ethers of form B (three) type 2-piperidylphenylmethanols.

According to the present invntion there are provided form B (threo) type ethers of unsubstituted or substituted 2-piperidylphenylmethanols of the general'formula:

G H-fAt 1 '-n. vrr-- u where represents a lower alleyl alkenyl group and. 60

Y practically inactive in this, fieldin therapeutically useful doses.

According to further features otthe present invention, the aforesaid new ethers of Formula II (forrn B) may be prepared by the.followiug methods employing'racemic rage; in this res eet ar those in whichiR is methyl eth propyl or isopropyl, andAr isphenyl, p-methoxypheuyh mixtures or optically active isomers of the starting mate: rials specified.

(1) Etherification of an unsubstituted orsubstituted 2-piperidylphenylmethanol of Formula I (form B) or an acid addition salt thereof by known methods for the etherification of aminoalcohols. During the etherification the nitrogen atom may be protected by a substituent which can readily be eliminated at the end of the reaction, such as a benzyl or acyl group. Preferably etherification is effected by the action of a reactive alkyl or alkenyl ester of formula RX (where R is as hereinbefore defined and X is an acid residue such as a halogen atom or a sulphuric or sulphonic ester residue) on an unsubstitu-ted or substituted 2-piperidylphenylmethanol of general Formula I (form B), in which the nitrogen atom of the piperidyl group is protected by a benzyl or acyl group. A basic condensation agent such as sodamide may be present with advantage.

The expression known methods as used in this specification and accompanying claims means methods heretofore used or described in the chemical literature. The expression substituted has reference solely to substitution in a phenyl group. The term lower as applied to alkyl and alkenyl groups means that the group in question has not more than four carbon atoms.

(2) Condensation of a chloro derivative of the general formula:

N GH-Ar A t.

III

(wherein and R are as hereinbefore defined) by known methods for the reduction of a pyridyl group to piper'idyl. Preferably the reduction is effected by hydrogenat ion in the presence of acatalyst, for examplepby means of hydrogen with the pyridyl ester in acetic acid in the presence of Adams platinum. I 7

- The racemic ethers obtained by the aforesaid ditferentf methods may optionally be sepaarted into the individual optically active isomers by direct resolution. The opti w I cally active ethers possess qualitatively analogous propl erties to those of'the racematesz they differ quantitatively, however, by the intensity of their activity which, com- 5 bined with notable differences in their secondaryeifects, renders their'use for therapeutic purposes probably moref advantageous. I y. 1 f

It is emphasised that" with the ethers of the present invention the period of excitation resulting from adminis trationj to animals is not followed by a period of depres-J sion as is the casewith certain other stimulants suchas for 'example, amphetamine. The ethersQof substituted 2fpip'eridylphenylmethanols (form B) conforminggto en eral Formula II are, therefore, useful in the treatment of states of fatigue 'ar'id depression Compounds of impo or 3:4-methylenedioxyphenyl; of particular importance is l-phenyl-l-ethoxy-1-(2-piperidyl)methane (form B).

For therapeutic purposes, the bases of general Formula II are preferably employed in. the form of acid addition salts containing pharmaceutically acceptable anions (such as hydrochlorides and other hydrohalides, phosphates, nitrates, sulphates, maleates, fumarates, citrates, tartrates, methanesulphonates and ethanedisulphonates).

The following examples illustrate the invention.

Example I A mixture of 1-phenyl-1-(l-benzyl-Z-piperidyl)methanol (form 13) (19.5 g.) and sodarnide (2.9 g.) in anhydrous toluene (450 cc.) is heated under reflux with agitation for 2 hours. After the mixture has been left to cool, methyl iodide (20 g.) is added and heating is continued for 2 hours. After cooling, the bases are extracted with 0.5 N hydrochloric acid (x50 cc.). The aqueous solutions are washed with ether and then made alkaline with sodium hydroxide. The yellowish oil formed is extracted with ether and the ethereal extracts are washed with water, dried and evaporated leaving an orange oil (12.5 g.) which is dissolved in acetic acid (200 cc.). The product is debenzylated by hydrogenation in the presence of 5% palladised charcoal (1.3 g.) at 80 C. under a pressure of kg./cm. The catalyst is filtered oil, the acetic acid is evaporated in vacuo and the residue is treated with water and made alkaline. The liberated debenzylated bases are extracted with chloroform. The chloroform solutions are washed with water, dried and evaporated in vacuo leaving an oil which is triturated with petroleum ether (20 cc.) A precipitate is formed which is washed and dried giving 1-phenyl-l-(Z-piperidyl) methanol (form B) (2.32 g.), that is to say an unetheri- Proceeding as in Example I but replacing the methyl iodide by ethyl iodide, there is obtained l-phenyl-l-ethoxyl-(2-piperidyl)methane hydrochloride (form B), MLP. 234 C.

Example III A mixture of 1-phenyl-1-(1-benzyl-2 piperidyl)rnetha; nol (form B) (193 g.), M.P. 91 C., and sodarnide (29.5 g.) in anhydrous benzene (3.75 litres) is heated underrefiux for 4 hours. A solution of ethyl toluene-p-sulphonate (180 g.) in anhydrous benzene (150 cc;.) is added gradually over minutes and boiling is. continued for 3 hours. The cooled reaction mixture is washed with water and extracted with dilute hydrochloric acid (0.5) N, 5 100 cc.) at 50 C. The hydrated hydrochloride of; l-phenyl-1-ethoxy-1-( 1-benzyl-2-piperidyl)methane (form B) (179 g.) precipitates from the dilute acid solutions from the extraction. After filtration and drying, itmelts at about 110 C. The base is liberated withsodium hydroxide and extracted with ether. A colourless oil (140 g.) is obtained which is dissolved in glacial acetic acid (1.1 litres). Debenzylation is efiected by hydrogenation in an autoclave at 70 C. under a pressure of 20 kg./cm. in the presence of 3.2% palladised charcoal (15 g.) for 3 hours. The catalyst is filtered 0E and washed with acetic acid (2X50 cc.) and the solvent is evaporated invacuo below 50 C. The residue from the evaporation is treated with distilled water (500 cc.), made alkaline with sodium hydroxide solution (d=1.33, 250 cc.) and extracted with ether (3 0.5 litre). After washing with water and drying, the ethereal solutions are evaporated leaving an oil which is treated with ether (120 cc.) containing about 15% hydrogen chloride. The precipitate obtained as, recrystallised from ethyl acetate (1.7 litres) containing 20% ethanol. There is obtained the hydrochloride, of l-phenyl-l-ethoxy-I-(Z-piperidyl)methane (form B) (74 g.), M.P. 234-235 C., identical with that described in Example II. On concentrating the liquors from the recrystallisation a second crop (16 g.) is obtained, M.P. 231 C.

Example IV Proceeding as in Example III but replacing the ethyl toluene-p-sulphonate by di-n-propyl sulphate there is obtained in 84.5% yield the hydrated hydrochloride of 1- phenyl 1 n-propoxy-l-(l-benzyl-2-piperidyl)methane (form B).

The last mentioned hydrochloride (22.4 g.) is debenzylated directly at 20 C. in acetic acid (250 cc.) under a slightly elevated pressure of hydrogen (about 10 cm. of water) in the presence of palladium (3.2%) on charcoal (8 g.). After filtration and evaporation of the acetic acid and washing with ether, there is obtained the hydro chloride of l-phenyl-l-n-propoxy-l-(2-piperidyl)methane (form B) (15.8 g.), M.P. 205 C., which on recrystallisation from butanone gives a product (13.2 g.), M.P. 210 C.

Example V Proceeding as in Example TV but replacing the di-npropyl sulphate by di-n-butyl sulphate there is obtained in 74% yield the, hydrated hydrochloride of l-phenyl-l-nbutoxy 1 (1-benzyl-2-piperidyl)methane. The correspondingyb ase (16.5 g.) is liberated with sodium hydroxide and extracted with ether and, after drying and evaporation, the residue from the evaporation is debenzylated at 20 C. in acetic acid in the presence of palladium (3.2%) on charcoal under a slightly elevated pressure of hydrogen. The. acetic acid is evaporated and the residue is treated with water, made alkaline with sodium hydroxide and extracted with ether. After drying, the ether is evaporated and the residual yellow oil (11.5 g.) is treated with ethyl acetate/(200 cc.). The addition of 15% ethereal hydrogen chloride (18 cc.) precipitates the hydrochloride of l-phenyl-l-n-butoxy-1-(2-piperidyl)- methane (form B) (9.5 g.), M.P. 189 C.

Example VI A mixture of 1-phenyl-1-(2-piperidyl)methanol (form B) (9.5 g.) and sodarnide (2.4 g.) in anhydrous benzene (200 cc.) is heated under reflux for 1 hour. A solution of ethyl toluene-p-sulphonate (12.3 g.) in anhydrous benzene (30 cc.) is added dropwise and boiling is continued for 2 hours. The cooled reaction mixture is washed with water cc.) and then extracted with 2 N hydrochloric acid (100 co. in 3 lots). The acid extracts are washed with ether, made alkaline with sodium hydroxide solution (d=1.33, 30 cc.) and the liberated bases are extracted with chloroform. After washing, drying over potassium carbonate and evaporation, a semicrystallineresidue is obtained which is triturated with petroleum ether (100 cc.). The insoluble crystals are the initial 1-phenyl-1-(2-piperidyl)methanol (4.5 g.; M.P. 172 C.). The oil (4.5 g.) obtained by evaporation of the filtrate is dissolved in butanone (30 cc.) and treated with 15 ethereal hydrogen chloride (6 cc.). There is obtained the hydrochloride of l-phenyl-l-ethoxy-l-(L piperidyl)methane (form B) (2 g.), identical with that described in Examples H and III.

Example VII mi u Q. l-p eny r my r2-piperidyl)methapot (form 13).,(11 g.), M.P. 133 C., and sodamide (2.15 g.) in anhydrous benzene (300 'cc.) is boiled1for3'hours. After cooling there is added ethyl iodide (9.4 g.) dissolved in anhydrous benzene (40 cc.). The mixture is then boiled for a further 4 hours. After cooling, the reaction mixture is washed successively with distilled water, dilute acid (0.5 N HCl), sodium bicarbonate and, finally, again with water. on drying over sodiu'm sulphate and evaporating there is obtained l-phenyl-b etl)1oxy- 1-(1-formyl-2-piperidyl)methane (form B) (6.7

A solution of this l-phenyl-1-ethoxy-1-(1-formyl-2- prperidyDmethane (1.35 g.) in'approximately 6%ethanolic hydrogen chloride (50 cc.) is heated under reflux for 24 hours, and the ethanol is then evaporated. The residue from the evaporation is treated with water, washed with benzene and then made alkaline with aqueous sodium hydroxide (d=1.33). After extraction with ether, drying and evaporating, the residue obtained (1.2 g.) is. triturated with petroleum ether. The insoluble fraction (0.14 g.) melts'at about 150 C. The residue (0.8 g.) from evaporation of the filtered petroleum ether gives, on the addition of ethereal hydrogen chloride, the hydrochloride of l-phenyl-l-ethoxy-1-(2-piperidyl)methane form B) (0.9 g.), identical with that described in Examples II, III and VI.

Example VIII A mixture of 1phenyl-1-(l-formyl-Z-piperidyl)methanol (form B) (29.6 g.), M.P. 133 C., and sodamide (5.9 g.) in anhydrous benzene (500 cc.) is boiled for 2 hours. Allyl bromide (19.5 g.) dissolved in benzene (50 cc.) is added and boiling is continued for 3 hours. A white precipitate is formed. After standing overnight at room temperature the reaction mixture is washed suc-- cessively with water, dilute hydrochloric acid, a 2% solution of sodium bicarbonate and water. It is then dried over sodium sulphate and evaporated. l-phenyl-l-allyloxy-'1-(l-formyl-Z-piperidyl)methane (29 g.) is obtained in the form of an orange oil which is deformylated by boiling for 24 hours in an approximately 7% solution (weight/ volume) (700 cc.) of hydrogen chloride in anhydrous methanol. The methanol is evaporated, the residue is treated with water and washed with ether and the aqueous phase is made alkaline. The liberated bases are.

extracted with ether (4x100 cc.) which is then dried over potassium carbonate and evaporated. There is thus obtained 1-phenyl-1-allyloxy 1. '1 (2 iperidyD methane (16.3 g.) in the form of an. oil. In order to prepare the 50 hydrochloride this oil is dissolved in ethyl acetate (200 cc.) and treated with (weight/volume) anhydrous ethereal hydrogen chloride cc.). The hydrochloride of '1 phenyl 1 allyloxy 1 (2 piperidyl)methane (form B) (17.3 g.) is precipitated, M.P. l80-181 C.; picrate, M.P. 174 C.

Example IX A mixture of laevorotatory 1-pheny1-1-( l-benzoyl-Z- piperidyl)methanol (form B) (14.5 g.) and sodamide (2.03 g.) in anhydrous toluene (500 cc.) is boiled for 1 /2 hours. A solution of ethyl iodide (10.4 g.) in anhydrous toluene cc.) is added and heating is continued for 2 hours. After standing overnight the toluene solution is washed successively with water (200 cc.), 2 N hydrochloric acid (250 cc.) and water. It is then dried over potassium carbonate and evaporated in vacuo at a temperature not exceeding 50 C. The residue from the evaporation is an oil (12 g.). It is dissolved in benzene (20 cc.) and petroleum ether (180 cc.) is added. There is precipitated laevorotatory l-phenyl-l-ethoxy-ll-benzoyl-Z-piperidyl)-methane (form B) (8.7 g.), M.P. 120-122 C., having the specific rotatory power [a] -99..4 (0:1, chloroform). lisation from cyclohexane (50 cc.) gives a product (7.53

An additional recrystaltatory l phenyl 1 ethoxy 1 (l-benzoyl-Z-piperidyl) methane (form B) (8.6 g.) thus obtained is 'debenzoylated by boiling for 4 hours in the presence of lithium aluminium hydride (0.67 g.) in tetrahydrof uran (260 cc.) freshly distilled over sodium. After cooling the mixture to 0 C. there are added successively with agitation distilled water (0.67 cc.), 4 N sodium hydroxide (0.67 cc.) and water (2.01 cc.). 'Agitation is continued for-20 minutes at 0 C. The inorganic precipitate is filtered oif' and treated with boiling tetrahydrofuran (50 Co.) for 15 minutes. After further filtration the combined tetrahydrofuran solutions are evaporated below 40 C. (under a pressure of 20 mm. Hg). The oily residue obtained (9 g.) is treated with ether and extracted with 2 N hydrochloric acid. The aqueous phase is made alkaline and the liberated bases are extracted with ether.

After washing with water, drying over potassium carbonate and evaporating, the residual oil (4.7 g is dis solved in ethyl acetate containing 10% ethanol (60 cc.) and converted into the hydrochloride by the addition of 15% anhydrous'ethereal hydrogen chloride (4.8 cc.).

The hydrochloride of laevorotatory l-phenyl-l-ethoxy- 1(2-piperidyl)-methane (form B) (2.55 g.), M.P. 260- 265 C., is obtained having the specific rotatory power: [a] =-70 (c=1, chloroform).

The laevorotatory 1-phenyl-l-(l-henzoyl-Z-piperidyl) methanol (form B) which serves as starting material is prepared by the action upon 1-phenyl-1-(2-piperidy1) methanol of the same configuration of an equal weight of pure benzoyl chloride in a mixture of N/ 2 potassium hydroxide and ether. It melts at C, and has the specific rotatory power: [a] =-108 (c=1, chloroform).

Example X The dextrorotatory hydrochloride of l-phenyl-l-ethoxyl-(2 -piperidyl)methane, (form B),' M.P. 260-265 C., (Maquenne), [a] +70 (c=1, chloroform), may be prepared in the samemanner as its antipode by the debenzoylation of dextrorotatory l-phenyl-l-ethoxy-l-(lbenzoyl-Z-piperidyl)methane (form B), M.P. 122 C. and having the specific rotatory power [a] =+1O2 (c=1,

chloroform), itself obtained from l-phenyl-l-(l-benzoyl- 2piperidyl)methanolof the same configuration, 170 C., [a] =+108, (c=.l, chloroform).

Example XI ethanol is evaporated, the residue is triturated with ether and there is obtained the hydrochloride of l-p-methoxyphenyl-l-ethoxy 1 (2 piperidyl)methane (form B) (3 g.) which melts at 237; C. after recrystallisation from.

methyl ethyl ketone or acetone.

In this and the following examples the chloro derivatives used as starting materials are obtained by the 'action of thionyl chloride upon the corresponding alcohols,

obtained by reduction of the corresponding ben zoyl pyr- I. 2

idines.

Example XII A solution of the hydrochloride of 1-(3z4-methylenedioxyphenyl) l (2 piperidyl)chloromethane (form' B), (8.8 g.), M.P. 160.516 1.5 C., in ethanol (50 cc.) is boiled for 2 hours. The formation of a white solid is observed and, on filtration, there is obtained {the hy-[ drochloride of 1-(3:4 methylenedioxyphenyl)-1-ethoxy- 1-(2-piperidyl)methane'(form B) (7 g.) which melts at 260 C. after recrystallisation from isopropanol.

Example XIIl.

Proceeding in the same manner as in Example Example XIV A solution of the hydrochloride of l-p-ethoxyphenyl- 1-(2-piperidyl)-chloromethane (form B) (6.5 g.), M.P. 168-169 C., in ethanol (50 cc.) is boiled for 2 hours. After concentration and the addition of ether there is obtained the hydrochloride of l-p-ethoxyphenyhl-ethoxy- 1-(2-piperidyl)rnethane (form B) (6 g.) which melts at 232 C. after recrystallisation from a mixture of isopropanol and isopropyl ether.

The present invention includes within its scope pharmaceutical compositions comprising one or more of the compounds of Formula II, or an acid addition salt thereof, and a significant amount of pharmaceutical carrier which may be either a solid material or a liquid.

Preparations for oral ingestion can be liquids or solids or any combination of these forms, such as solutions, suspensions, syrups, elixirs, emulsions, powders or tablets. Pharmaceutical preparations for administration of the acetive therapeutic agents in unit dose form can take the form of compressed powders (or tablets) or of a powder enclosed in a suitable capsule of absorbable material such as gelatin. These compressed powders (or tablets) can take the form of the active materials admixed with suitable excipients and/or diluents such as starch, lactose, stearic acid, magnesium stearate or dextrin.

In yet a further embodiment, the active material may, as such or in the form of a diluted composition, be put up in powder packets and employed as such.

Preparations for parenteral administration may be sterile solutions or suspensions in water or other liquids, with or without the addition of soluble or insoluble diluents and/or solid or liquid excipients.

The percentage of active ingredient in the compositions of the invention may be varied, it being necessary that it should constitute a proportion such that a suitable dosage shall be obtained. Obviously several unit dosage forms may be administered at about the same time. In general, the preparations of the present invention should normally contain at least 0.02% by weight of active substance in the case of injectable solutions and. at least 0.01% by weight of such substance in the case of oral preparations.

We claim:

1. A member of the class consisting of the racemates and optically active isomers of compounds of the formula:

N C H-AI l BIO-R wherein R is selected from the class consisting of methyl, ethyl, n-propyl, n-butyl, isopropyland allyl and AI is selected from the class consisting of phenyl, p-methoxyphenyl, 3,4-methylene dioxyphenyl, and p-ethoxyphenyl and acid addition salts of the said compounds which have pharmaceutically acceptable anions;

. 2. A member of the class consisting of l-phenyl-lmethoxy-l-(Z-piperidyl)methane (form B) and its acid addition salts which have pharmaceutically acceptable 31310118.

3. A member of the class consisting of l-phenyl-l-eth- OXy-I-(Z-piperidyl)methane (form B) and its acid addition salts which have pharmaceutically acceptable. anions, and optical isomers.

4. A member of the class consisting of l-phenyl-l-npropoxy-l-(2-piperidyl)methane (form B) and its acid additions salts which have pharmaceutically acceptable anions.

5. A member of the class consisting of l-phenyl-l-nbutoxy-l-(2-piperidyl)methane (form 13) and its acid addition salts which have pharmaceutically acceptable anions.

6. A member of the class consisting of l-phenyl-lallyloxy-1-(2-piperidyl)methane (form B) and its acid addition salts which have pharmaceutically acceptable anions.

7. A member of the class consisting of l-p-methoxyphenyl-l-ethoxy-1-(2-piperidyl)methane (form B) and its acid addition salts which have pharmaceutically acceptable anions.

8. A member of the class consisting of l(3:4-methy1- enedioxyphenyl) -1-ethoxy-1- (Z-piperidyl methane (form B) and its acid addition salts which have pharmaceutically acceptable anions.

9. A member of the class consisting of l-(3z4-methylenedioxyphenyl)-1,-isopropoxy-1 (2 piperidyl)methane (form B) and its acid addition salts which have pharmaceutically acceptable anions.

10. A member of the class consisting of 1-p-ethoxyphenyl-1-ethoxy-1-(2-piperidyl)methane (form B) and its acid addition salts which have pharmaceutically acceptable anions.

References Cited in the file of this patent Anker et al.: Chemical Society Journal (1945), pp. 917-920.

Heer et al.: Helv. Chim. Acta (Swiss), vol. 38 (1955 pp. 134-140.

Karrer: Organic Chemistry, 2nd ed. (1946), Elsevier Pub. Co., New York, pp. 92-102.

-al-L 

1. A MEMBER OF THE CLASS CONSISTING OF THE RACEMATES AND OPTICALLY ACTIVE ISOMERS OF COMPOUNDS OF THE FORMULA: 